Xanthan gels were assessed to control the reductive dechlorination of hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs) in a strong permeability contrast and high velocity sedimentary aquifer. An alkaline degradation was selected because of the low cost of NaOH and Ca(OH)₂. The rheology of alkaline xanthan gels and their ability to deliver alkalinity homogeneously, while maintaining the latter, were studied. Whereas the xanthan gels behaved like non-Newtonian shear-thinning fluids, alkalinity and Ca(OH)₂ microparticles had detrimental effects, yet, the latter decreased with the shear-rate. Breakthrough curves for the NaOH and Ca(OH)₂ in xanthan solutions, carried out in the lowest permeability soil (9.9 μm²), demonstrated the excellent transmission of alkalinity, while moderate pressure gradients were applied. Injection velocities ranging from 1.8 to 3.8 m.h^-1 are anticipated in the field, given the permeability range from 9.9 to 848.7 μm². Despite a permeability contrast of 8.7 in an anisotropic aquifer model, the NaOH and the Ca(OH)₂ both in xanthan gels spread only 5- and 7-times faster in the higher permeability zone, demonstrating that the delivery was enhanced. Moreover, the alkaline gels which were injected into a high permeability layer under lateral water flow, showed a persistent blocking effect and longevity (timescale of weeks), in contrast to the alkaline solution in absence of xanthan. Kinetics of alkaline dechlorination carried out on the historically contaminated soil, using the Ca(OH)₂ suspension in xanthan solution, showed that HCHs were converted in TCBs by dehydrodechlorination, whereas the latter were then degraded by reductive hydrogenolysis. Degradation kinetics were achieved within 30 h for the major and most reactive fraction of HCHs.

评估了黄原胶以控制六氯环己烷（HCH）和三氯苯（TCB）的还原脱氯，并具有很强的渗透性对比和高速沉积含水层。由于NaOH和Ca（OH）_2的成本低，因此选择了碱性降解方法。研究了碱性黄原胶的流变性及其在保持碱度的同时均匀地传递碱度的能力。尽管黄原胶的行为类似于非牛顿剪切稀化流体，但碱度和Ca（OH）₂微粒具有有害作用，但后者随剪切速率而降低。为氢氧化钠和Ca（OH）穿透曲线₂（9.9微米黄原胶溶液，在最低渗透土壤进行²），表现出了极好的碱度传递，同时施加了适度的压力梯度。注射速度范围为1.8至3.8 MH ^-1预计在该领域，考虑到透气性范围从9.9到848.7微米²。尽管在各向异性含水层模型中渗透率对比度为8.7，但NaOH和Ca（OH）₂黄原胶中的两种化合物在较高渗透率区域中的传播速度仅快5倍和7倍，这表明传递能力得到了增强。此外，与不存在黄原胶的碱性溶液相比，在侧向水流下注入高渗透性层的碱性凝胶显示出持久的阻断作用和寿命（几周的时间尺度）。使用在黄原胶溶液中的Ca（OH）₂悬浮液，在历史污染的土壤上进行碱性脱氯的动力学表明，六氯环己烷通过脱氢脱氯转化为TCB，而后者随后通过还原氢解而降解。六氯环己烷的主要和最具反应性的部分在30小时内达到了降解动力学。